Learn ARM easily: Play with buzzer

Today we are going to learn how to easily learn the ARM series and play with the buzzer, based on the Samsung S5PV210 development platform of the ARM cortex_a8 core.

So let's see how to learn to use pwm to control the buzzer?

1. Overall Architecture Diagram

Before we can solve the buzzer problem, we need to have a certain understanding of the relevant chapters of Samsung's GPIO introduction, mainly the timer.

2. Several tips for playing with timers

2.1 Check the schematic diagram of the buzzer connection on the development board

Schematic diagram of the buzzer

The corresponding schematic diagram of the core board

2.2 Select the xpwmTOUT1 function of the GPD0CON configuration register

GPD0.GPD0CON = ((~(0xf 0)) & GPD0CON) | (0x2 << 4); Select PWM output function

2.3 Configuration of pre-scaling and frequency division registers

Configure the prescaler value, TIMER.TCFG0 = (TIME.TCFG0 & (~0xff)) | 0xff;

The prescaler value is set to 255 + 1

Configure the frequency division value to 16:

TIMR.TCFG1 = (TIME.TCFG1 & (~0xf0)) | (0x4 << 4);

2.4 Set the register value of the buffer counter and the value of the buffer comparator

Working principle: The value of the counter is decremented by 1 every clock cycle. If the value is equal to the value of the comparator, a high-low level conversion is performed, and the counter continues to decrement by 1 until it reaches 0, then it flips to achieve a complete square wave cycle.

Set the count buffer register value

        TIME.TCNTB1 = XXX; Set the total cycle, one pwm

        Set the compare buffer register value

        TIME.TCMPB1 = XXX/2; Setting is duty cycle

2.5 Manually update the value in the buffer register to the counter

Steps to set up pwm:

According to the second step of 1.3.15, first set the manual update, then clear the manual update and start the timer

Manual update, update the value in the buffer to the counter, double buffer mechanism

TIME.TCON = TIME.TCON & (0x0e << 8); 0000 1110

Clear the manual update bit and start the timer. 0000 1101 0x0d

TIME.TCON = TIME.TCON & (0x0d << 8);